Mobile crane



W. TAYLOR MOBILE CRANE Dec; '16; 1952 2 SHEETSAHEET 1 Filed Oct. 16,1947 myenzon HEM 2. y

Dec. 16, 1952 w. TAYLOR 2,621,803

MOBILE CRANE Filed Oct. 16. 1947 2 SHEETS-SHEET 2 Patented Dec. 16,1.952

UNITED STATES PATENT OFFICE Application October 16, 1947, SerialNo."780,1 14 In Great Britain October 1-8, 1946 3 Claims. 1

This invention relates to improvements in mobile cranes of the typehaving a mechanically or hydraulically operated j-ib.

The object of the invention is to provide means for enabling the end ofthe jib to be brought down to or below the level of the vehicle on whichthe crane is mounted.

According to the invention the jib is formed in two parts pivotallyconnected together, the means for raising and lowering the jib operatingon the rear part and the front part being so controlled that it pivotsabout the rear part as the latter is raised and lowered.

The invention is illustrated in and will be described with reference tothe accompanying drawings in which:

Fig. l is a side elevation showing the jib in the lowered and in theraised positions;

Fig. 2 is a side elevation drawn to a larger scale of the front part anda portion of the rear part of a slightly modified form of jib adapted tocarrying an excavating bucket or other device on the free end of thefront part;

Fig. 3 is a section on the line 3-3 of Fig. 2; and

Fig. 4 is a side elevation of the adjoining ends of the two parts of thejib separated from one another.

The main jib of the crane is formed in two parts A and A The rear end ofthe front part A is pivotally mounted on a bar a at the front end of therear part A The rear part A is pivoted at b on a balance box B mountedat the rear of a motor vehicle and is raised or lowered by a hydraulicram 01' rams C or by other mechanical means preferably operated by theengine of the vehicle. The ram or rams C or other means may act directlyon the rear part A of the jib but it is preferred, as shown in Fig. 1,to employ a secondary jib A below the main jib, the secondary jib Abeing pivoted at b on the balance box B. The ram or farm C act on thesecondary jib A and the latter carries at its free end a roller orrollers a which engages an inclined surface a on the underside of thefront end of the rear part A of the main jib. By this means a greaterlift is given to the part A for a given movement of the ram or rams thanif the latter acted directly on the part A A bell crank or two armedlever D is bolted on each side of the rear of the front part A so thatthe levers D and the front part A will pivot together in relation to therear part A The end d of each lever D is pivotally con- *2 nected to oneend of rod E the other end of which is pivoted at b on the balance boxB. The. pivotal point D is in front of. and below the point I) at whichthe rear part A is pivoted so that the length of the rod E is less thanthe distance between the bar a. and the pivot point I) about which therear portion A of th main jib turns.

When the main jib is in its raised position, i. e. the upper positionshown in Fig. 1, the two parts A and A are substantially in alignmentbut as the jib is lowered the rods E cause the front part A to pivitabout the rear part A so that when the rear part has reached or almostreached its lowest position, i. e. the bottom position shown in Fig. 1or Fig. 2, the front part A is at an angle to the rear part with itsfront end level with the ground or if desired below the level thereof ifthere is a hole or trench to receive it.

As the jib is raised the front part A is. con strained by the rods E topivot, about the front end of the rear part A so that when the jib israised to its top position the two parts A and A are again insubstantial alignment.

A jib of a mobile crane constructed according to this invention has theadvantage that its front end can be brought down to ground level therebyin many cases facilitating the connection of the work to be raised tothe weight hook and it has the further advantage also resulting from thefact that its front end can be brought down to or below ground levelthat it can be used as an excavating or like device.

When it is intended that the crane should be employed for excavating orother purposes instead of or in addition to its normal function ofraising and transporting work, the front end a of the front part A is asshown in Fig. 2 of tapered form to receive the tapered socket g of anexcavating bucket G or of any other devised device, the socket 9 beingsecured to the tapered end 01. by one or more transverse pins or bars 9I claim:

1. A mobile crane including a motor chassis forming a mobile support; amain jib formed of a rear jib portion pivotally mounted at the rear endthereof upon the motor chassis and a forward jib portion pivotallyconnected at the rear end of the same to the forward end of the saidrear jib portion movable between a raised and a lowered position; anauxiliary jib also pivotally mounted at the rear end thereof upon thechassis independently of the pivot mounting of the rear jib portion andhaving a roller thereon engaging the underside of said rear jib portion;a ram mounted on said chassis and engageable with the auxiliary jib forraising and lowering the auxiliary jib whereby to raise and lower therear jib portion and thereby also the main jib; and link means at oneend operatively connected to the rear end of said forward jib portioneccentrically of the pivot connection between said forward and rear jibportions, and at its other end operatively connected to the chassis at apoint spaced from the pivot mounting of said rear jib portion thereonand causing said forward jib portion to pivot on said forward end of therear jib portion to its raised position when said main jib is raised,and to its lowered position when said main jib is lowered.

2. A mobile crane including a motor chassis forming a mobile support; amain jib formed of a rear jib portion pivotally mounted at the rear endthereof upon the motor chassis and a forward jib portion pivotallyconnected at the rear end of the same to the forward end of said rearjib portion; an auxiliary jib also pivotally mounted at the rear endthereof upon the chassis independently of the pivot mounting of the rearjib portion and having a roller thereon engaging the underside of saidrear jib portion; a ram mounted on said chassis and engageable with theauxiliary jib for raising and lowering the auxiliary jib whereby toraise and lower the rear J'ib portion and thereby also the main jib; andat least one rod forming a link pivotally connected at one end to saidchassis at a point below and spaced from the pivot mounting of said rearjib portion thereon and operably connected at its forward end to theforward jib portion eccentrically of the pivot connection between saidforward and rear jib portions in order to control the latter and enablethe forward end of said forward jib portion to be brought down belowground level while the forward end of said rear jib portion is disposedabove ground level when said main jib is lowered by said ram.

3. A mobile crane including a motor chassis having a balance box; a mainjib formed of a rear jib portion pivotally mounted at the rear endthereof upon the balance box and a forward jib portion pivotallyconnected at the rear end of the same to the forward end of said rearjib portion; an auxiliary jib also pivotally mounted at the rear endthereof upon said balance box forwardly of the pivot mounting of saidrear jib portion thereon and at a lower level than the latter pivotmounting and having a roller at the forward end engaging beneath therear jib portion; at least one rod forming a link pivotally connected atthe rear end thereof to the balance box intermediate the pivot mountingof said rear jib portion and auxiliary jib and pivotally connected atthe forward end thereof to the rear end of the forward jib portioneccentrically and independently of the pivot connection between saidforward and rear jib portions; and a ram pivotally connected at one endto said chassis and engageable with the auxiliary jib for raising andlowering said auxiliary jib and thereby raising and lowering said mainjib.

WILLIAM TAYLOR.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Taylor Mar. 28, 1950

